1. Field of the Invention
The present invention relates to a keyless entry system mounted, for example, on the four-wheel vehicle (hereinafter referred to as vehicle).
2. Description of the Related Art
A wireless keyless entry system using a feeble electric current intended for use in the vehicle is already put into actual use. It is constructed in such a manner that a signal including the identification code supplied from the transmitter provided as a portable electronic key (remote controller) by the operation of the user such as a driver is received by the receiver via an antenna, and when the identification code is determined to be correct, the action intended by said user, such as the open/close operation of the door lock, is controlled.
In many cases, the receiver in such a system is disposed in the trunk room or in the dashboard, and the antenna is installed on the rear glass or the upper portion of the dashboard remote from the receiver. Therefore, the wiring connecting the antenna and the receiver requires a shielding process in order to prevent external noise that may enter from the environment, whereby the cost may be increased.
As a measure to solve this problem, a structure having a receiver integrated within the combination meter mounted in front of the driver's seat, and an antenna is mounted on the meter board or in the meter housing is disclosed in the Japanese Patent Laid-Open No.8-216735. In this arrangement, the shielding process is eliminated and the number of the component may be reduced, thereby realizing reduction of the cost.
However, in this system, the high receiving sensitivity is required as a matter of course. Though the most effective measure to realize the high receiving sensitivity is upsizing of the antenna, it has been difficult to realize since mounting of the antenna on the combination meter is physically limited due to the size of the meter.